Although hypothermia (low core body temperature) can be harmful in many situations, it has been found to provide some therapeutic advantages. Therefore, it may be intentionally induced as therapeutic hypothermia. For example, periods of cardiac arrest in the setting of myocardial infarction and heart surgery can produce brain damage or other nerve damage. In the medical community, hypothermia is considered as an accepted neuroprotectant during cardiovascular surgery. A patient may be maintained in a state of induced hypothermia during cardiovascular surgery. Hypothermia is also sometimes induced as a neuroprotectant during neurosurgery. Therapeutic hypothermia can be used beneficially to prevent or reduce the effect of tissue damage from ischemic injuries and other injuries. For example, tissue damage that follows ischemic injuries can begin at the onset of ischemia and continue throughout the reperfusion phase after blood flow is restored. Both preclinical and clinical studies support the observation that the reperfusion phase can last from hours to days, and that therapeutic hypothermia can be used beneficially to block much of the injury in that phase.
In the case of cardiac arrest (a global ischemia), therapeutic hypothermia is considered the standard of care for neuroprotection purposes. Under standard protocol, whole body hypothermia can be performed by reducing core body temperature to between 32° C. and 35° C. for about 12 to about 24 hours after return of circulation. However, whole body hypothermia presents numerous difficulties. Lowering the systemic temperature of a patient not only takes a significant amount of time, but also can subject the patient to deleterious side effects of hypothermia including cardiac arrhythmias, coagulation problems, increased susceptibility to infections, and problems of discomfort such as profound shivering. Compensating for these side effects also may require a pharmacological regime with its own risks or negative side effects.